crypto/ec/ec_check.c

   1 /*
   2  * Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "ec_lcl.h"
  11 #include <openssl/err.h>
  12
  13 int EC_GROUP_check_named_curve(const EC_GROUP *group, int nist_only,
  14                                BN_CTX *ctx)
  15 {
  16     int nid = NID_undef;
  17 #ifndef FIPS_MODE
  18     BN_CTX *new_ctx = NULL;
  19
  20     if (ctx == NULL) {
  21         ctx = new_ctx = BN_CTX_new();
  22         if (ctx == NULL) {
  23             ECerr(EC_F_EC_GROUP_CHECK_NAMED_CURVE, ERR_R_MALLOC_FAILURE);
  24             goto err;
  25         }
  26     }
  27 #endif
  28
  29     nid = ec_curve_nid_from_params(group, ctx);
  30     if (nid > 0 && nist_only && EC_curve_nid2nist(nid) == NULL)
  31         nid = NID_undef;
  32
  33 #ifndef FIPS_MODE
  34  err:
  35     BN_CTX_free(ctx);
  36 #endif
  37     return nid;
  38 }
  39
  40 int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
  41 {
  42 #ifdef FIPS_MODE
  43     /*
  44     * ECC domain parameter validation.
  45     * See SP800-56A R3 5.5.2 "Assurances of Domain-Parameter Validity" Part 1b.
  46     */
  47     return EC_GROUP_check_named_curve(group, 1, ctx) >= 0 ? 1 : 0;
  48 #else
  49     int ret = 0;
  50     const BIGNUM *order;
  51     BN_CTX *new_ctx = NULL;
  52     EC_POINT *point = NULL;
  53
  54     if (group == NULL || group->meth == NULL) {
  55         ECerr(EC_F_EC_GROUP_CHECK, ERR_R_PASSED_NULL_PARAMETER);
  56         return 0;
  57     }
  58
  59     /* Custom curves assumed to be correct */
  60     if ((group->meth->flags & EC_FLAGS_CUSTOM_CURVE) != 0)
  61         return 1;
  62
  63     if (ctx == NULL) {
  64         ctx = new_ctx = BN_CTX_new();
  65         if (ctx == NULL) {
  66             ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
  67             goto err;
  68         }
  69     }
  70
  71     /* check the discriminant */
  72     if (!EC_GROUP_check_discriminant(group, ctx)) {
  73         ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
  74         goto err;
  75     }
  76
  77     /* check the generator */
  78     if (group->generator == NULL) {
  79         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
  80         goto err;
  81     }
  82     if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {
  83         ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
  84         goto err;
  85     }
  86
  87     /* check the order of the generator */
  88     if ((point = EC_POINT_new(group)) == NULL)
  89         goto err;
  90     order = EC_GROUP_get0_order(group);
  91     if (order == NULL)
  92         goto err;
  93     if (BN_is_zero(order)) {
  94         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
  95         goto err;
  96     }
  97
  98     if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
  99         goto err;
 100     if (!EC_POINT_is_at_infinity(group, point)) {
 101         ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
 102         goto err;
 103     }
 104
 105     ret = 1;
 106
 107  err:
 108     BN_CTX_free(new_ctx);
 109     EC_POINT_free(point);
 110     return ret;
 111 #endif /* FIPS_MODE */
 112 }